Segments - Revenue Reconciliation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Revenue
Revenue	$ 17,618	$ 17,560	$ 54,093	$ 53,253
Business Segments
Revenue
Revenue	19,064	19,193	58,678	57,870
Other revenue
Revenue
Other - divested businesses	(3)	4	(2)	36
Other revenue	20	46	47	127
Internal transactions
Revenue
Revenue	$ (1,463)	$ (1,683)	$ (4,631)	$ (4,780)